The Devil can possess you.
Devil, or Satan, whatever you have called it, has always possessed people since the Human was first created. What happens is the Devil, after his last possessed victim dies a horrible, unspoken death, he moves into its next victim, entering though either the mouth or the ears, depending on gender, and when it reaches the brain, you die. The Devil now owns your body, for one day.
Can it possess other people while one is already possessed? No, The Devil only can possess one person at a time. What The Devil often does is possess a person with a dangerous past, filled with gripes, pain, and misery. It then has one task. It goes to a family member, breaks the neck violently, slits its own wrist, puts the blood into the family members mouth, then drags the family member into a pond (If you want to know why, let's just say it's a "Trademark"), and then the body is destroyed into blood, nothing else. The body implodes on itself so no one can discover the devils being, but leaves a hint with the drop of blood in the mouth of the victim.
Possess is not a word that should be used often. Only the Devil, his followers, and firm believers should use the word, as if you do, you'll be one step closer to Hell. Why, you may ask? Possessing is believed to be a myth, and we want it to STAY that way, no objections. So, use it at your own risk, a risk that your soul possibly depends on.
You should not make fun of the Devil in any way possible, as if you do, it's just as bad as believing in possession itself. As you see, your God cannot protect you in anyway possible. So, if you parody or mock The Devils power, you could have a chance of being possessed, either in this life, or the next. Oh, and as you were reading this, you're probably wondering who I am.
Well, if I did, all I'd have to say is, The Devils gonna come for you, not now, but soon...